Reducing ores and forming sponge metals and alloys



June 20, 1944.

B. A..JEFFERY REDUCING ORES AND FORMING SPONGE METALS AND ALLOYSBenjam/z /LJeffery @MMM @mi yFiled Dec. 12, 1941 had.. .v 1

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Patented June 20, 1944 REpUcING oar-:s AND FORMING sPoNGE v METALS ANDALLoys Benjamin A. Jeffery, Clarkston, Mich., assignor of one-half toScott H. Lilly, Toledo, Ohio Application December 12, 1941, Serial No.422,670

(Cl. l-34) 11 Claims.

This invention relates to the reduction of metals, the forming of spongemetal, and the making of alloys.

The purpose of theinvention is to provide a new and improved process forreducing ores and particularly in that type of operations where thereduction takes place without complete fusion.

Another object of the invention is to prepare the ore in an advantageousway so that it may be reduced, if desired, in a stack by well knownmeans.

Another object of the invention is to provide a method byA which ore maybe reduced Without fusion and with high uniformity.

Another object of the invention is to provide a method by which spongemetal may be produced advantageously and of high uniformity.v

Another object of the invention is to provide a method whereby alloys'ormixtures may be produced with great uniformity and with any desiredproportions of 'the respective ingredients.

Other objects and minor details of the invention will appear as thedescription proceeds.

One application of the invention will be described in some detail andthen variations of the application of the invention will be indicated.

In the accompanying drawing forming a, part of this application there isdisclosed somewhat diagrammatically apparatus which may be employed incarrying out one form of the invention. 'I'he apparatus indicated in thedrawing comprises a refractory base II) upon which there is mounted akiln Within the kiln there is a concentric lining member |2 spacedinward from the outer wall. In the construction disclosed, the kiln isapproximately circular in horizontal crosssection. Through the top ofthe kiln there projects a pipe I3 on the lower end of which there is aspraying device I4 indicated diagrammatically. In practice, this may bea pair of discs spaced apart and mounted for rotation.

Within the base member and below the kiln, there is a downwardlytapering recess I5 leading to a central opening I6. Resting upon thesurface of the recess I5 immediately surrounding opening I 6 there is aconical plate I1. In the wall of the recess I5 beneath plate I1 there isone or more recesses or an annular recess |8 in which there are mountedsuitable burners |9. A space 20 is provided between plate I1 and rthesurface of recess I5 above the recess or recesses I8.

A downdraft flue 2| projects vertically through the opening I6 andupward into the kiln, the upper end being open at 22. Over this openupper end there is a conical cap 23. Mounted upon flue 2| just aboveplate |1 there is a substantially parallel plate 24. A plate 25 restingupon the upper edge of plate 24 tapers upwardly to the flue 2| near itsupper end. yIn the construction shown, a plurality of ballles 28 areprovided on plate 25 beneath cap 23.`

A receptacle 21 is attached to base Il) beneath Y opening I6 and aninlet pipe 28 discharges into receptacle 21 around flue 2|. Passageway29 between plates I1 and 2| forms a continuation of the passagewaybetween flue 2| and receptacle 21 and discharges at its upper end at thelower edge of lining plate I2 so that passages 20 and 29 bothcommunicate to some extent with the bottom of passage 30 between kilnand its liner |2. As shown, the liner is spaced downward slightly fromthe top ofthe kiln so that passageway 30 communicates at the top withthe chamber 3| within liner |2, and passageway 29 also communicates withchamber 3 I.

In the construction shown, liner I2 is shown as suspended at the top bybrackets 32.

'I'he bottom of receptacle 21 is downwardly tapered at 33 to a dischargegate 34 from which a discharge pipe 35 leads downward.

Presuming that the apparatus described is to be employed in reducingiron ore, the procedure is as follows:

The iron ore is rst procured in the form of a powder or reduced to aline powder. This powder is mixed with fluid, which may be water, toapproximately the consistency of a thick clay slip. Preferablycarbonaceous material is mixed throughout the slip evenly.

After the slip has been thoroughly mixed so that it is uniformthroughout, it is discharged downward through pipe |3 and sprayed byspraying means I4 so that it is thrown horizontally outward from thatspraying means in the 4form of small drops.

As will be readily seen from an examination of the drawing, the productsof combustion from burner I9 blow upward in the direction indicated bythe arrows through passageways 20 and 30 and are discharged into the topof chamber 3|, from which they are discharged through ue 2|. At the sametime, carbon monoxide or other gases may be introduced, if desired,through pipe 28.

When the drops of slip encounter the heated gases, they are dried intothe form of round pellets which drop downward and encounter'surface 25from which they slide into passageway 29, and from thenceinto receptacle21. If desired, bailles may be placed upon the upper surface ofplatesv25 and/or Il so as to delay the passage of the material, and itwill be readily understood that the angle to the horizontal of theseparts may be varied as the requirements of the particular materialemployed and the purpose for which it is to be used make advisable.

The dried pellets of material, if the spraying is properly controlled,will be approximately spherical in form and will roll readily, and evenif the construction is such that passageway 29 is completely lled withthese pellets, there 'will still be ready passageway for the heatinggases. During the entire heating period, the gases will contact thesurface of each pellet readily. It will be readily seen that bycontrolling the kind and quantity and temperature of gases introducedthrough pipe 428 and the discharge from burners I9 and the amount andcharacter of carbonaceous material in the slip, the temperature can bequite accurately controlled atsuccessive points, and the temperature atwhich reduction takes place can he adjusted as desired.

Of course, 'if desired, the plate I1 might be made of suitable materialand the temperature raised su-iliciently high to fuse the metal as itflows over the plate above the burners. Ordinarily, however, it ispreferable to employ this method in connection with the reduction of theore without fusion.

It has frequently been proposed hitherto to mix iron ore andcarbonaceous material and feed it downward through a stack whilecontrolling the temperature so as to reduce the ore without fusion. Suchattempts have encountered many dilculties. It has been found difllcultto feed the material uniformly and evenly downward through the stack. Ithas been found difficult to maintain the body ,of material within thestack sufficiently permeable so that gases would readily contact allparts. As a consequence, it is very diflicult to maintain uniformtemperature or uniform access of the various gases and fuels todifferent portions of the ore, and consequently some portions might becarbonized to an imdesired extent, while some would be insufficientlyreduced and others heated more than is desirable. It has been recognizedthat the results of the reduction vary quite materially with variationsin the temperature and a method by which it can be rendered uniform isconsequently an important improvement in this respect.

In the apparatus disclosed, it will be seen that the products ofcombustion at first heat the passageway 29, which may be consideredroughly equivalent to the stack previously proposed, pass upward andthen are employed for drying and preheating the ore before it reachesthe stack. This arrangement is preferred because of its simplicity andeconomy in the use of fuel. However, it will be readily understood thatthe broad principles of the method could be carried out by spraying anddrying the ore in one apparatus and then collecting this dried ore inpellet form and introducing it into any desirable stack. lBecause of thepellet form and its free flowing characteristics, it will readily passthrough any suitable stack and at the same time allow passage of thegases which are employed to treat the material.

into pellets in the manner described and the reduction might take placeby means of the reducing gases brought into contact with the pel- Thetreatment lends itself readily to the reduction of the ore at atemperature materially below the melting point of the iron; The materialso produced will be delivered in pellet form porous and readilypermeable because of the passageways between the pellets. The individualpellets also may be porous, as indicated above, if reduced at acomparatively low temperature, or if preferred, the temperature may beraised so that the individual pellets may be relatively solid.

The treatment in this manner is simplified if the ore is relativelypure. However, the same method'may be employed to advantage where thereis a material amount of slag present. Under these circumstances, thetemperature may be raised suillciently so that the `iron in each pelletwill form a core with the slag surrounding it. The slag may then beremoved from the pellets by tumbling or other rubbing and cleaningoperation. With certain kinds of ores, the removal of the slag may befacilitated .by dropping the pellets While still heated into a suitablecooling medium which chills the slag suddenly and thereby loosens itfrom the iron ore.

While the method has been described in connection with the treatment ofiron ore, it will be readily apparent that it might be employed withadvantage for reducing oxides of iron in lieu of the method disclosed,for examplein Patent No. 2,085,178, and similar uses where it isdesirable to have the iron in finely divided form, and at the same time,it is desirable to have it in a form which can be readily handled. By

While this method is particularly suitable for spray drying iron sludgewhich had been employed in a chemical process resulting in its oxidationand then reducing the dried pellets, the iron could be promptly andeasily recovered in a condition which would permit its advantageoushandling and with the exact degree of porosity preferred.

While reference has been made above to the reduction of iron ore, itwill be readily understood that other ores which are susceptible toreduction in a similar manner might be treated by this process. In otherwords, it would be advantageous in a case where the ore is to besubjected to the action of gases to form the ore into a slip and spraydry in pellet form so that it will be uniformly and thoroughlyaccessible to treatment by gases and at the same time may be readilyhandled and passed through the treating apparatus. If desired, differentmaterials may be very uniformly distributed throughout the mass to betreated by mixing the powder in slip form and then spray drying. By thistreatment, the material is distributed in the spray dried form asuniformly as in the slip. It is dicult to obtain such uniformdistribution by other means. Because of this uniform distribution, it isrelatively easy to distribute different kinds of ore and/or metal sothat the composite pellets when treated will form a desired alloy.

While the steps disclosed above are particularly adaptable for preparingmaterial for reduction renders it adaptable for forming alloys startingwith the powdered metal, if preferred. In that case, the powdered metalmay be formed into a slip, the liquid employed being treated or modiiiedin each case so as to produce the desired suspension of the metalparticles in the i slip. When a slip of metal particles is spray dried,these particles will be uniformly distributed in the dried pellets. ifthey are uniformly distributed in the slip. Thereafter, these pelletsmay be heated to such a degree as to cause the interaction of thedifferent metals to produce alloys or combinations of metal withoutcomplete fusion, and the uniform distribution is maintained. This isadvantageous wherever sponge metal is to be formed of an alloy as willbe clear from the foregoing description. Also, mixtures of metals may beformed in this way and by proper treatment sintered and compacted so asto form solid metal without affording the opportunity for segregationwhich occurs when the material is melted and poured into a mold forcasting.

Not only could the material be prepared by spray drying as describedabove for reduction, for forming sponge metal, or for forming alloys,and then reduced or otherwise treated in a stack or like furnace, but,if desired, similar uniform mixes might be produced by spray drying,then molding or forming into any desired shape and heating by anysuitable furnace, electric or otherwise.

What I claim is:

1. The method of obtaining metal from ore where the metal may beobtained by contact of fluid with the ore, which comprises forming aslip of the powdered ore and a vaporizable liquid, spraying the slipinto separated drops, drying the drops-into pellets, and contacting thepellets with a fluid by contact with which the metal is obtained fromthe ore.

2. The method of reducing ore, which comprises forming a slip of thepowdered ore and a vaporizable liquid, spraying the slip into separateddrops, drying the drops into pellets, and subjecting the pellets toreducing gas at a reducing temperature.

3. The method which comprises forming a slip of powdered oxide of ironsuspended in a vaporizable liquid, spraying the slip into separateddrops, drying the drops into pellets, and reducing the oxide of iron inthe pellets to metallic iron.

4. The method of reducing ore, which comprise forming a slip of thepowdered ore suspended. in a vaporizable liquid and mixed withcarbonaceous material, mixing the ore and material evenly throughout theslip, spraying the slip into separated drops, drying the drops intopellets, and contacting the pellets with heated gas until the desiredreduction has been eiected.

5. The method of reducing oxide of iron, which comprises forming a slipof the powdered oxide of iron suspended in a vaporizable liquid andmixed with carbonaceous material, mixing the oxide of iron and materialevenly throughout the slip, spraying the slip into separated drops,drying the drops into pellets, and contacting the pellets with heatedgas until the desired reduction has been effected.

6. The method of forming an alloy which comprises forming a slip ofpowdered material suspended in a vaporizable liquid. said materialcomprising metals in the proportions desired for the alloy, mixing thematerial evenly throughout the slip, spraying the slip into separateddrops, drying the drops into pellets, contacting thepellets with heatedgas untilthe metals are sintered together, and stopping the heaiiingbefore complete fusion takes place.

7. The method of forming an alloy which comprises forming a slip ofpowdered material suspended in a vaporizable liquid, said materialcomprising atoms of metals in the proportions desired for the alloy, atleast some of said atoms being in oxide molecules, mixing the materialevenly throughout the slip, spraying the slip into separated drops,drying the drops into pellets, contacting the pellets with heatedreducing gas until the metals are sintered together, and stopping theheatingbefore complete fusion takes place.

8. The method of forming an alloy which comprises forming a slip ofpowdered material suspended in a vaporizable liquid, said materialcomprising atoms of metals in the proportion desired for the alloy andalso comprising carbonaceous material, at least part of said atoms beingin' oxide molecules, mixing the materials evenly throughout the slip,spraying the slip into separated drops, drying the drops into pellets,and contacting the pellets with hot gas until the oxide is suitablyreduced and the metals are sintered together.

9. The method of making sponge iron, which comprises forming a slip ofpowdered iron ore and carbonaceous material in a vaporizable liquid,mixing the materials evenly throughout the slip, spraying the slip intoseparated drops, drying the drops into pellets, contacting the pelletswith hot gas until the desired reduction has taken place, and stoppingthe heating before the pellets are completely fused.

10. The method which comprises forming a slip of powdered iron ore andslag-producing material in a vaporizable liquid, spraying the slip intoseparated drops, drying the drops into pellets, contacting the pelletswith heated gas under reducing conditions until the ore is reduced,continuing the heating until the slag is segregated on the exterior ofthe pellets, then suddenly subjecting the exterior of the pellets to acooling medium and separating the metal cores of the pellets from theslag segregated on their exteriors.

11. The method of forming porous metal articles, which comprises forminga slip of suspended metalliferous material, spraying the slip intoseparated drops, drying the drops into pellets, eliminating non-metallicmaterial from the metalliferous material in the pellets, introducing themetallic pellets into a mold, and adhering the pellets together withoutentirely closing the passages between the pellets.

BENJAMIN A. JEFFERY.

